Fluorosilicone elastomer rubber is used in many automotive and industrial applications because of their resistance to extreme environmental and service conditions. These elastomers retain their elastomeric properties over a broad temperature range. For example, in some applications these materials can be exposed to temperatures below −40° C., or even below −100° C., for an extended period of time. In other applications, they can be used in environments having a temperature of 200° C. or even higher. In addition, fluorosilicone elastomers generally have excellent resistance to fuels and oils, making them useful for sealing applications in aerospace, automotive, and chemical processing industries.
One drawback of fluorosilicone elastomers has been their limited resistance to polar solvents, hydrocarbon fluids, and brake fluids containing phosphate esters.
U.S. Pat. No. 6,815,492 B2 (Sato et al.) discloses a curable fluoropolyether rubber composition containing: (A) a linear fluoropolyether compound having at least two alkenyl organic groups per molecule and a backbone with a perfluoropolyether structure; (B) an organosilicon compound having at least two silicon-bonded hydrogen atoms (SiH organic groups) per molecule; (C) a hydrosilylation catalyst; and (D) a silica filler. The rubber compositions are said to have good resistance to: fuels, jet engine oils, amines, and oils, gas permeability, water, heat, and cold. Curing was accomplished by hydrosilylation using a hydrosilylation catalyst. Hydrosilylation catalysts are generally expensive. Furthermore, as the catalyst is not incorporated in the polymer, these metal compounds may tend to leach out of the rubber composition and cause contamination issues.
There remains a need for new methods and materials for making fluorosilicone elastomers.